1. Field of the Invention
The present invention relates to a slide drive device for a press. The slide drive device provides a stroke adjusting function in which a dead center position is fixed and a slide strike is adjustable. The dead center position may be either a top or bottom dead center position.
2. Description of the Related Art
Japanese Laid Open Patent Publication Numbers 7-132400,11-77398, and 11-197888 are examples of slide drive devices for presses that use links equipped with a stroke adjusting function.
In Japanese Laid-Open Patent Publication Number 7-132400, the slide stroke can be changed with an adjustment at one position. Making a stroke correction is difficult in this device since the adjustment position is at a branching point for a left and right drive. When the stroke is changed, the bottom dead center position also changes. When the stroke is lengthened, mechanical acceleration at the top dead center is greatly increased.
In Japanese Laid-Open Patent Publication Number 11-77398, the left and right slides have separate slide stroke adjustment mechanism. Each mechanism must be adjusted separately. During use, there is a loss of precision due to operational backlash. During adjustment, each slide must be adjusted individually. Since each mechanism is separate there may be a loss of left-right balance. Further, although the bottom dead center position does not change with the change in the stroke, the pitch between the points cannot be narrowed by the adjusting mechanism disclosed.
As in the previous device, in Japanese Laid-Open Patent Publication Number 11-197888, a slide stroke is similarly adjusted between separate left and right slides. When the precision of the adjustment mechanism deteriorates, there is the possibility of a breakdown of balance between the left and right side.